Solvent effects on the intramolecular conversion of trimethylsulfonium chloride to dimethyl sulfide and methyl chloride

2014 ◽  
Vol 16 (48) ◽  
pp. 26658-26671 ◽  
Author(s):  
Timm Lankau ◽  
Chin-Hui Yu
Keyword(s):  
Solvent Effects ◽  
Dimethyl Sulfide ◽  
Ion Pairs ◽  
Methyl Chloride

M05/6-311+G(2d,p) calculations reveal the role of ion pairs in the conversion of (CH3)3SCl as a function of solvent's permittivity.

Can the Lewis basicity of an isolated solvent molecule be used for characterizing solvent effects?

2020 ◽  
Vol 16 ◽  
Author(s):  
Jean-François Gal ◽  
Pierre-Charles Maria
Keyword(s):  
Solvent Effects ◽  
Molecular Level ◽  
Solvent Molecule ◽  
Lewis Base ◽  
Bulk Liquid ◽  
Donor Number ◽  
Special Focus ◽  
Solution Processes ◽  
Inert Solvent

Background: The ubiquitous Lewis acid/base interactions are important in solution processes. Analytical chemistry may benefit of a better understanding of the role of Lewis basicity, at the molecular level or acting through a bulk solvent effect. Objective: To clearly delineate (i) the basicity at a molecular level, hereafter referred as solute basicity, and (ii) the solvent basicity, which is a bulk-liquid property. Method: The literature that relates Lewis basicity scales and solvent effects is analyzed. A special focus is placed on two extensive scales, the Donor Number, DN, and the BF3 affinity scale, BF3A, which were obtained by calorimetric measurement on molecules as solutes diluted in a quasi-inert solvent, and therefore define a molecular Lewis basicity. We discuss the validity of these solute scales when regarded as solvent scales, in particular when the basicity of strongly associated liquids is discussed. Results: We demonstrate the drawbacks of confusing the Lewis basicity of a solvent molecule, isolated as solute, and that of the bulk liquid solvent itself. Conclusion: Consequently, we recommend a reasoned use of the concept of Lewis basicity taking clearly into account the specificity of the process for which a Lewis basicity effect may be invoked. In particular, the action of the Lewis base, either as an isolated entity, or as a bulk liquid, must be distinguished.

Copolymerization of Isobutene and Isoprene at “High” Temperature with Syncatalyst Systems Based on Aluminum Organic Compounds

1976 ◽  
Vol 49 (4) ◽  
pp. 937-959 ◽  
Author(s):  
S. Cesca ◽  
M. Bruzzone ◽  
A. Priola ◽  
G. Ferraris ◽  
P. Giusti
Keyword(s):  
Energy Savings ◽  
Ion Pairs ◽  
Great Part ◽  
Methyl Chloride ◽  
Reactivity Ratio ◽  
Experimental Conditions ◽  
Noticeable Increase ◽  
Catalyst Systems ◽  
Kinetics Of ◽  
Kinetics Of Vulcanization

Abstract New catalyst systems based on alkylaluminum derivatives and halogen or interhalogen compounds were found highly efficient in the synthesis of high-molecular-weight IIR at temperatures above − 50°C. The reaction mechanism was studied in detail for the system Et2AlCl + Cl2. The reactions occurring between chlorine, isobutene, Et2AlCl, and the solvent (CH3Cl) were elucidated and studied under various experimental conditions (e.g. presence or absence of light, simultaneous presence of the copolymerization system components, temperature, type of halogen, use of model compound of isobutene). It was concluded that halogenium ions, i.e. Cl+, Br+, or I+, are the initiating species. Kinetic and conductometric investigations showed that scarcely dissociated ion pairs, e.g. Cl+[Et2AlCl2]−, were formed in the absence of monomer; but in the presence of isobutene, a noticeable increase of the electrical conductivity and rapid polymerization occurred. The maximum polymerization rate was first order with respect to the concentrations of monomer, Cl2, and Et2AlCl. In the homopolymerization of isobutene, transfer to monomer and termination reactions were negligible. The MW of IIR was found to be mainly dependent on the concentrations of the catalyst components, on isoprene concentration, and on temperature. The reactivity ratio of isobutene with isoprene was found to be r1=2.5±0.5 at −35°C, while the activation energies relative to MW were −5.8 ± 0.4, kcal/mol for polyisobutene, and −5.7 ± 0.7 and − 4.3 ± 0.5 kcal/mol for IIR containing, respectively, 1.3 and 1.9 mol% of isoprene. The evaluation of some physicochemical and technological properties of typical IIR produced with the system Et2AlCl + Cl2, indicated that isoprene is randomly distributed along the chains and that the MWD is monomodal, while the glass transition temperature, tensile properties, mechanical-dynamic spectra, and kinetics of vulcanization are very similar to those of commercial IIR. Very preliminary data, referring to several classes of new catalyst systems yielding IIR having good properties, were also obtained. The syncatalyst systems here described can work in a homogeneous phase consisting of an aliphatic hydrocarbon besides methyl chloride, still giving IIR with high MW. Therefore, a completely homogeneous process can be envisioned for the synthesis of IIR at −50°C thus avoiding a great part of the fouling problems of the slurry process. The economic advantage of using “high” temperatures of polymerization is briefly discussed in terms of energy savings.

The effect of the trisulfur radical ion on molybdenum transport by hydrothermal fluids

2021 ◽  
Author(s):  
Maria A. Kokh ◽  
Clement Laskar ◽  
Gleb S. Pokrovski
Keyword(s):  
Composition Range ◽  
Ion Pairs ◽  
Primary Source ◽  
Econ Geol ◽  
Hydrothermal Conditions ◽  
Earth Planet ◽  
Porphyry Deposits ◽  
Experimental And Theoretical Studies ◽  
Partitioning Behavior

<p>Knowledge of molybdenum (Mo) speciation under hydrothermal conditions is a key for understanding the formation of porphyry deposits which are the primary source of Mo. Existing experimental and theoretical studies have revealed a complex speciation, solubility and partitioning behavior of Mo in fluid-vapor-melt systems, depending on conditions, with the (hydrogen)molybdate (HMoO<sub>4</sub><sup>-</sup>, MoO<sub>4</sub><sup>2-</sup>) ions and their ion pairs with alkalis in S and Cl-poor fluids [1-3], mixed oxy-chloride species in strongly acidic saline fluids [4, 5], and (hydrogen)sulfide complexes (especially, MoS<sub>4</sub><sup>2-</sup>) in reduced H<sub>2</sub>S-bearing fluids and vapors [6-8]. However, these available data yet remain discrepant and are unable to account for the observed massive transport of Mo in porphyry-related fluids revealed by fluid inclusion analyses demonstrating 100s ppm of Mo (e.g., [9]). A potential missing ligand for Mo may be the recently discovered trisulfur radical ion (S<sub>3</sub><sup>•-</sup>), which is predicted to be abundant in sulfate-sulfide rich acidic-to-neutral porphyry-like fluids [10]. We performed exploratory experiments of MoS<sub>2</sub> solubility in model sulfate-sulfide-S<sub>3</sub><sup>•-</sup>-bearing aqueous solutions at 300°C and 450 bar. We demonstrate that Mo can be efficiently transported by S<sub>3</sub><sup>•-</sup>-bearing fluids at concentrations ranging from several 10s ppm to 100s ppm, depending on the fluid pH and redox, whereas the available data on OH-Cl-S complexes cited above predict negligibly small (<100 ppb) Mo concentrations at our conditions. Work is in progress to extend the experiments to wider T-P-composition range of porphyry fluids and to quantitatively assess the role of S<sub>3</sub><sup>•-</sup> in Mo transport by geological fluids.</p><ul><li>1. Kudrin A.V. (1989) <em>Geochem. Int. </em><strong>26</strong>, 87–99.</li> <li>2. Minubayeva Z. and Seward T.M. (2010) <em>Geochim. Cosmochim. Acta</em> <strong>74</strong>, 4365–4374.</li> <li>3. Shang L.B. et al. (2020) <em>Econ. Geol. </em><strong>115</strong>, 661–669.</li> <li>4. Ulrich T. and Mavrogenes J. (2008) <em>Geochim. Cosmochim. Acta </em><strong>72</strong>, 2316-2330.</li> <li>5. Borg S. et al. (2012) <em>Geochim. Cosmochim. Acta</em> <strong>92</strong>, 292–307.</li> <li>6. Zhang L. et al. (2012) <em>Geochim. Cosmochim. Acta</em> <strong>77</strong>, 175–185.</li> <li>7. Kokh M.A. et al. (2016) <em>Geochim. Cosmochim. Acta </em><strong>187</strong>, 311–333.</li> <li>8. Liu W. et al. (2020) <em>Geochim. Cosmochim. Acta</em> <strong>290</strong>, 162–179.</li> <li>9. Kouzmanov K. and Pokrovski G.S. (2012) <em>Soc. Econ. Geol. Spec. Pub.</em> <strong>16</strong>, 573–618.</li> <li>10. Pokrovski G.S. and Dubessy J. (2015) <em>Earth Planet. Sci. Lett. </em><strong>411</strong>, 298–309.</li> </ul>

scholarly journals First Evidences of Methyl Chloride (CH3Cl) Transport from the Northern Italy Boundary Layer during Summer 2017

Atmosphere ◽  
2020 ◽  
Vol 11 (3) ◽  
pp. 238 ◽  
Author(s):  
Paolo Cristofanelli ◽  
Jgor Arduini ◽  
Francescopiero Calzolari ◽  
Umberto Giostra ◽  
Paolo Bonasoni ◽  
...  
Keyword(s):  
Boundary Layer ◽  
High Frequency ◽  
Stratospheric Ozone ◽  
Methyl Chloride ◽  
Temporal Correlation ◽  
Northern Italy ◽  
Montreal Protocol ◽  
Anthropogenic Activity ◽  
Bivariate Analysis

Methyl Chloride (CH3Cl) is a chlorine-containing trace gas in the atmosphere contributing significantly to stratospheric ozone depletion. While the atmospheric CH3Cl emissions are predominantly caused by natural sources on the global budget, significant uncertainties still remain for the anthropogenic CH3Cl emission strengths. In summer 2007 an intensive field campaign within the ACTRIS-2 Project was hosted at the Mt. Cimone World Meteorological Organization/Global Atmosphere Watch global station (CMN, 44.17° N, 10.68° E, 2165 m a.s.l.). High-frequency and high precision in situ measurements of atmospheric CH3Cl revealed significant high-frequency variability superimposed on the seasonally varying regional background levels. The high-frequency CH3Cl variability was characterized by an evident cycle over 24 h with maxima during the afternoon which points towards a systematic role of thermal vertical transport of air-masses from the regional boundary layer. The temporal correlation analysis with specific tracers of anthropogenic activity (traffic, industry, petrochemical industry) together with bivariate analysis as a function of local wind regime suggested that, even if the role of natural marine emissions appears as predominant, the northern Italy boundary layer could potentially represent a non-negligible source of CH3Cl during summer. Since industrial production and use of CH3Cl have not been regulated under the Montreal Protocol (MP) or its successor amendments, continuous monitoring of CH3Cl outflow from the Po Basin is important to properly assess its anthropogenic emissions.

scholarly journals Contact Ion Pairs on a Protonated Azamacrocycle: the Role of the Anion Basicity

2016 ◽  
Vol 27 (4) ◽  
pp. 615-621 ◽  
Author(s):  
Caterina Fraschetti ◽  
Antonello Filippi ◽  
Maria Elisa Crestoni ◽  
Enrico Marcantoni ◽  
Marco Glucini ◽  
...  
Keyword(s):  
Ion Pairs ◽  
Contact Ion Pairs

Solvent Effects in Carbohydrate Binding by Synthetic Receptors: Implications for the Role of Water in Natural Carbohydrate Recognition

2008 ◽  
Vol 120 (14) ◽  
pp. 2733-2736 ◽  
Author(s):  
Emmanuel Klein ◽  
Yann Ferrand ◽  
Nicholas P. Barwell ◽  
Anthony P. Davis
Keyword(s):  
Solvent Effects ◽  
Carbohydrate Binding ◽  
Synthetic Receptors ◽  
Carbohydrate Recognition
Sign in / Sign up

Export Citation Format

Share Document